Ergopeptines are a group of ergot alkaloids and are, moreover, secondary metabolic products formed by plant-associated fungi of the genus Claviceps belonging to the Clavicipitaceae family.
The most prominent member of this genus is Claviceps purpurea, which above all affects cereals like rye, wheat, tricitale, barley and maize. Another member, namely Claviceps africana, is widely found in millet. Further ergot alkaloid-producing fungi of this family include grass endophytes of the genus Epichloë, Neotyphodium and Balansia, yet also Aspergillus fumigatus and various Penicillium spp. are able to produce ergot alkaloids.
In general, ergot alkaloids have a characteristic skeletal structure with a tetracyclic ergoline ring that comprises a methylated nitrogen at the 6-position and may have different substituents at the C-8 position. Based on these substituents, ergot alkaloids are categorized into clavines, simple lysergic acid amides, ergopeptines and ergopeptams.
 R1R2ErgopeptineCH3CH(CH3)2ErgovalineCH3CH2C6H5ErgotamineCH3CH2CH(CH3)2α-ErgosineCH(CH3)2CH(CH3)2ErgocomineCH(CH3)2CH2C6H5ErgocrystineCH(CH3)2CH2CH(CH3)2α-Ergocryptine
Due to their structural similarity with neurotransmitters, ergot alkaloids interact with the receptors of the latter, causing a plurality of effects such as intoxications, yet also positive actions in the pharmaceutical field. Today, ergot alkaloids no longer constitute problems in the human field because of improved cleaning techniques in mills. However, they still contribute to problems in animal husbandry, causing a plurality of adverse symptoms. The symptoms caused by ergot alkaloids in animals, in particular, comprise gangrene, lameness, a reduced weight gain, an increased respiratory frequency, a reduced serum prolactin level, a reduced milk production, and a low reproduction rate. In this respect, the endophytes encountered in pasture grasses in America, New Zealand and Australia first of all raise problems in animal husbandry. Thus, the endophyte infection of tall fescue by Neotyphodium coenophialum has caused high losses to livestock producers.
For the majority of the above-described effects or symptoms, ergopeptines, which constitute the group with the highest multiformity of the ergot alkaloids, are responsible, which, in turn, are themselves categorized according to the amino acid directly bound to D-lysergic acid. In this respect, the characteristic oxazolidin-4-ring of the ergopeptines is referred to as cyclol ring according to the nomenclature used by Schardl et al. Members are represented by the ergotamine group comprising, inter alia, ergotamine, ergovaline and ergosine, in which the first amino acid is L-alanine. A further group is the ergotoxine group, in which the first amino acid bound to D-lysergic acid is L-valine. Representatives of the latter include ergocristine, ergocryptine or ergocomine. Still a further member is the ergoxine group, in which the first amino acid bound to lysergic acid is an α-aminobutyric acid. Representatives are ergostine and ergonine.
Among these, ergovaline is one of the main alkaloids of the Neotyphodium and Epichloë species endophytically growing in pasture grasses and is of veterinary-toxicological relevance, e.g. in fescue toxicosis. 9,10-dihydroergopeptines only rarely occur in nature and have so far only been detected in Sphacelia sorghi. Partially synthetically obtained dihydroergopeptines such as dihydroergotamine and dihydroergotoxine have therapeutic relevance in the treatment of migraine and cardiovascular diseases. Apart from the described positive effects, in particular the therapeutic relevance of ergopeptines, their toxic action is, however, of non-negligible significance, since, in particular, their toxicity due, for instance, to the consumption of contaminated grains or toxic endophytes will result in the destruction or impairment or damage of numerous physiological systems such as the reproductive organs, the growth-oriented systems and the cardiovascular structures within the body of an animal or human being. Furthermore, there is presently no doubt that the consumption of grains infested with ergotamines or ergopeptines will also directly affect the gastrointestinal system and hence strongly impair not only the health of animals, but also their performances.